It is known, in the prior art, different solutions, and particularly that described in the patent application W02014/091152 describing a mechatronic unit for positioning a member comprising a control unit and an actuator. The control unit (ECU) includes a servo algorithm and a power bridge. It drives the power bridge, delivering a two-wire electrical signal composed of a torque signal and a steering signal. The actuator comprises an N-phase multi-phased brushless electric motor, binary probes for detecting the position of the rotor of this motor, power switches suitable for supplying the N phases of the motor from the two-wire electrical signal. The state of the power switches is controlled directly by a signal coming from the sensing probes.
In this document, the two-wire signal including the torque information, the steering information and also drives the power (voltage/current) used by the motor phases.
The solution proposed in the prior art is particularly effective for low power electric motors.
However, for stronger power motors, the direct supply of the power bridge by the signals from an ECU implies power losses by Joule effect. Also, the ECUs are not generally known for strong power management which may lead to a lack of reliability and a significant material cost.
It is also known that patent application US2012/068642 describes a single-phase control device for a brushless DC motor, pulse width modulation (PWM) and a switching logic unit for controlling the speed and rotation of a single-phase motor.
The structure of a single-phase motor provides for a number of poles identical to the stator and the rotor, and a control mode specific to such an iso-polar architecture. The teaching of such a control device cannot be transposed to a multi-phased motor. Indeed, a multi-phased motor comprises a stator consisting of excitation coils which are generally 3 or 6 (this is an indicative example). These are most often star-connected, but they can also be connected in delta. The rotor consists of permanent magnets with 2 to 8 poles with an alternation of the North and South poles.
Most BLDC motors also include a set of three Hall effect sensors that, positioned at 60° or 120° from each other, know the position of the rotor. Knowing the rotor's position allows an auxiliary electronic circuit to switch the power supply. A multi-phased motor is controlled by a switching sequence which is fundamentally different from the control of a single-phase motor and it is therefore not obvious to a person skilled in the art to combine teachings relating to a motor and a single-phase control, for designing a motor and a multi-phased driver circuit.
The purpose of this invention will be restricted to multi-phased motors where N is greater than 1. For motors where N=1 (mono-phased motor), the skilled professional admits that the start-up sequence and the means to impose rotation steering is not trivial and generally and generally uses an electronic circuit to steer the complex and intelligent motor (eg a microcontroller).